var foo = "";
foo = 1;
foo = {};

typeof undefined;//-> undefined
typeof 0; //-> number
typeof true; //-> boolean
typeof {}; //-> string
typeof []; //-> object
typeof null; //-> object
typeof ""; //-> object
typeof new String(""); //-> object
typeof alert; //-> object

"foobar".toLowerCase();

new String("foobar").toLowerCase();

/* object type */
var obj = {}; // new object()
obj['foo'] = 'bar';
obj.foo = 'bar';

var obj = {
	foo : 'bar';
}; 



/* undefined and null */
var foo;
typeof foo; //=> undefined

var foo = null; 
typeof foo; //=> object


